1. Field of the Invention
The present invention relates to a coordinate measuring machine that performs a scanning measurement using a probe including a contact-type measurement tip, and a method for calculating a correction matrix by a coordinate measuring machine.
2. Description of Related Art
A coordinate measuring machine is generally used in combination with a probe. If the coordinate system on the main body side of the coordinate measuring machine matches the coordinate system of the probe, the drive detection value {xm, ym, zm}T of the coordinate measuring machine, which is represented by the coordinate system on the main body side of the coordinate measuring machine, and the probe detection value {xp, yp, zp}T, which is represented by the coordinate system of the probe, are added, to thereby calculate the measurement result {x, y, z}T as shown in the following Expression (1).
                              {                                                    x                                                                    y                                                                    z                                              }                =                              {                                                                                x                    m                                                                                                                    y                    m                                                                                                                    z                    m                                                                        }                    +                      {                                                                                x                    p                                                                                                                    y                    p                                                                                                                    z                    p                                                                        }                                              (        1        )            
On the other hand, if the coordinate system on the main body side of the coordinate measuring machine does not match the coordinate system of the probe, an error occurs. The occurrence of the error due to the mismatch between the coordinate systems can be reduced by coordinate conversion using a correction matrix as shown in Expression (2), and various methods for calculating the correction matrix have been proposed.
                                          {                                                                                x                    p_m                                                                                                                    y                    p_m                                                                                                                    z                    p_m                                                                        }                    =                                    [                                                                                          A                      11                                                                                                  A                      12                                                                                                  A                      13                                                                                                                                  A                      21                                                                                                  A                      22                                                                                                  A                      23                                                                                                                                  A                      31                                                                                                  A                      32                                                                                                  A                      33                                                                                  ]                        ⁢                          {                                                                                          x                      p                                                                                                                                  y                      p                                                                                                                                  z                      p                                                                                  }                                      ⁢                                  ⁢        where                            (        2        )                                          [                                                                      A                  11                                                                              A                  12                                                                              A                  13                                                                                                      A                  21                                                                              A                  22                                                                              A                  23                                                                                                      A                  31                                                                              A                  32                                                                              A                  33                                                              ]                ⁢                  :                ⁢                                  ⁢        CORRECTION        ⁢                                  ⁢        MATRIX                            (                  2          ′                )            {xp_m, yp_m, zp_m}T: the probe detection value obtained by converting the coordinate system of the probe into the coordinate system on the main body side of the coordinate measuring machine.
The measurement result {x, y, z}T which is obtained by taking into consideration an error is expressed by the following Expression (3).
                              {                                                    x                                                                    y                                                                    z                                              }                =                              {                                                                                x                    m                                                                                                                    y                    m                                                                                                                    z                    m                                                                        }                    +                      {                                                                                x                    p_m                                                                                                                    y                    p_m                                                                                                                    z                    p_m                                                                        }                                              (        3        )            
In this regard, Published Japanese Translation of PCT International Publication for Patent Application, No. 2009-534681 proposes a method for performing a scanning measurement of a reference sphere with a first push-in amount, further performing a scanning measurement of the reference sphere with a second push-in amount, and calculating the correction matrix by using detection values obtained as a result of the measurements.
Published Japanese Translation of PCT International Publication for Patent Application, No. 2005-507495 proposes a method for performing a scanning measurement of a reference sphere while continuously changing a push-in amount on a movement path parallel to a chord of the reference sphere or on a sinusoidal path, and for calculating the correction matrix by using detection values obtained as a result of the measurement.